The present invention relates to vacuum waste systems and methods for operating such systems.
Vacuum waste systems are generally known in the art in which one or more waste receptacles, such as a toilets or galley waste sinks, fluidly communicate with a collection tank. The tank is connected to a vacuum generator, such as a vacuum blower or pump, which is operable to create a partial vacuum in the tank. A flush valve, which opens in response to a flush command, is disposed between each receptacle and the waste tank to control fluid communication between the receptacle and the waste tank.
When installed on an aircraft, such vacuum waste systems typically have a bypass line, which allows the system to operate in low altitude and high altitude modes. The bypass line establishes fluid communication between the collection tank and the atmosphere outside the aircraft, without passing through the vacuum generator. A check valve is typically provided in the bypass line to allow direct communication only when the atmospheric pressure is sufficiently lower than the ambient air pressure inside the aircraft cabin. As a result, the vacuum waste system may be operated in the low altitude mode when the aircraft is on the ground or flying at lower altitudes, typically below 16,000 feet. In this mode, the vacuum generator is used to create the partial vacuum level in the waste tank. When the flush command is generated, the flush valve opens, and the pressure differential between the ambient cabin air pressure at the receptacle and the partial vacuum pressure in the collection tank transports waste in the receptacle to the waste tank.
The high altitude mode of operation is used when the aircraft is operating at higher altitudes, such as above 16,000 feet. It will be appreciated that the atmospheric pressure at high altitudes is reduced, and therefore the cabin of the aircraft must be pressurized. As a result, a pressure differential between the pressurized cabin air and the high altitude atmospheric pressure exists that may be used to transfer waste from the receptacle to the tank. Accordingly, the vacuum generator is switched off and the check valve in the bypass line is opened to create partial vacuum in the tank. The flush valve may then operate as described above to transport the waste.
The vacuum generators typically used in vacuum waste systems are designed to handle air only, and therefore are extremely intolerant of contamination. As a result, care must be taken to isolate the vacuum generator from waste and rinse fluid transported by the vacuum waste system. Separation of contaminants from the air is particularly difficult due to the large amount of air that is pulled in by the system during operation. The incoming air may create a rapid air stream that may easily become entrained with liquid contaminants from the receptacle or tank. To prevent liquid contaminants from reaching the vacuum generator or being ejected out of the aircraft through the bypass line, an air/liquid separator is typically provided at the collection tank. In addition, the collection tank is often oversized to provide spacing between the vacuum port on the tank and the fluid level in the tank. The water separator and oversized tank take up additional space and add weight to the system, considerations which are particularly important in aircraft applications.
In addition, the amount of air drawn into conventional vacuum waste systems can be excessive, thereby generating unwanted noise. When the flush valve is opened in a typical vacuum waste system, an uninterrupted air flow path is created from the receptacle to the vacuum source. As a result, the entire volume of the system that is placed under partial vacuum is relatively large, and therefore excessive air is rapidly drawn into the system. Furthermore, the vacuum source maybe operating when the flush valve is open, such as during high altitude mode, and therefore still more air is drawn into the vacuum waste system. The large vacuum volume and continued vacuum source connection may cause the air to enter through the receptacle at a high velocity, thereby generating noise.
Accordingly, it is evident that a vacuum waste system is needed which isolates the vacuum source from liquid contaminants while reducing the size and weight of the system, and further reduces noise generated during operation of the system.
In accordance with certain aspects of the present invention, a vacuum waste system is provided having a receptacle for receiving waste, the receptacle having an outlet. A collection tank is in fluid communication with the receptacle outlet, and a vacuum source fluidly communicates with the collection tank to produce a partial vacuum in the collection tank. A flush actuator is operable to generate a flush command, and a flush valve is disposed between the toilet outlet and the collection tank having a normally closed position, the flush valve actuating to an open position for a flush interval in response to the flush command, thereby to control fluid communication between the collection tank and toilet outlet. A vacuum control valve is disposed between the vacuum source and the collection tank, the vacuum control valve being operable between open and closed positions thereby to control fluid communication between the collection tank and vacuum source, the vacuum control valve being operably linked to the flush valve so that the vacuum control valve is operated in the closed position during at least a portion of the flush interval.
In accordance with additional aspects of the present invention, a vacuum waste system is provided for use on an aircraft, the vacuum waste system comprising a receptacle for receiving waste, the receptacle having an outlet, and a waste pipe having a first end connected to the receptacle outlet and a second end. A collection tank has a waste inlet port connected to the waste pipe second end and a vacuum port, and a flush actuator is provided which is operable to generate a flush command. A flush valve is disposed in the waste pipe having a normally closed position, the flush valve actuating to an open position for a flush interval in response to the flush command, thereby to control fluid communication between the collection tank and toilet outlet. A common pipe has a first end attached to the vacuum port and a second end, and a vacuum pipe has a first end and a second end, the vacuum pipe first end being in fluid communication with the common pipe second end. A bypass pipe has a first end in fluid communication with the common pipe second end, and a second end, and a discharge pipe has a first end in fluid communication with the vacuum pipe second end and bypass pipe second end, and a second end in fluid communication with atmosphere outside the aircraft, the atmosphere having a reduced pressure at higher altitudes to provide a vacuum source. A vacuum generator is disposed in the vacuum pipe for generating a partial vacuum in the collection tank when the aircraft is at lower altitudes. A vacuum control valve is disposed in the common pipe, the vacuum control valve being operable between open and closed positions thereby to control fluid flow through the common pipe, the vacuum control valve being operably linked to the flush valve so that the vacuum control valve is operated in the closed position during at least a part of the flush interval.
In accordance with further aspects of the present invention, a method of operating a vacuum waste system is provided to control air flow through the system during a flush cycle. The vacuum waste system includes a receptacle having an outlet, a collection tank in fluid communication with the receptacle outlet, a vacuum source in fluid communication with the collection tank to produce a partial vacuum in the collection tank, a flush actuator associated with the flush valve, the flush actuator operable to generate the flush command, a flush valve disposed between the toilet outlet and the collection tank operable between open and closed positions, and a vacuum control valve disposed between the vacuum source and the collection tank operable between open and closed positions. The method comprises normally operating the flush valve in the closed position, actuating the flush valve to the open position for a flush interval in response to the flush command, and operating the vacuum control valve in the closed position during at least a part of the flush interval, thereby to limit air flow out of the collection tank.
Other features and advantages are inherent in the apparatus claimed and disclosed or will become apparent to those skilled in the art from the following detailed description and its accompanying drawings.